Double-throw knife switch



Aug. 26, 1930. H HAMMERLY 1,774,479

DOUBLE THROW KNIFE SWITCH Filed June 5 1929 3 Sheets-Sheet 1 INVENTOR Herman miner-(y,

N EY Aug. 26, 1930. H. .1. HAMMERLY DOUBLE-THROW KNIFE SWITCH Filed June 5, 1929 3 Sheets-Sheet 5 ,j. 1mm early :13 I Q h INVENTOR H erm an K14 Patented Aug. 26, 1930,

UNITED STATES PATENT OFFICE mum? J. nammnnnzor wanmiveronn, comvnc'rrcu'r, assrenon r0 THE raun- BULL. nnncrnrc MANUFACTURING COMPANY, or rmmvrnnn, connncrrcur, a

CORPORATION OF CONNECTICUT DOUBLE-THROW KNIFE SWITCH 'Appllcation filed June 5, 1829. Serial No. 868,849.

This invention relates articularly to enclosed electric switches oi the double-throw type in which the pivotally mounted switch blades are arranged to be moved by an external operatmg handle so as to en- 4 gage either of two sets of co-operating stationary contacts positioned at opposite sides of the posts -.on which the blades are mounted.

One object of my invention is to provide a double-throw switch having detachable cross-bar connections between the blades and the operating member so arranged that the switch may be secured in or removed from the enclosing box without disturbing the operating member'and so that the crossbar members are secured .in operable position solely by securing the switch base in position in the box.

- Another object is to provide a novel form of double-throw switch blade which is particularly adapted for use in connection with quick-make and quick-break mechanism for the reason that the substantially parallel contact portions of the blade allow forapplying the quick-make movement to the blade long before the blade has approached its co-operating stationary blade and for applying the quick-break movement to the blade before the blade has separated from its co-operating stationary contact in the circuit opening movement."

Anotherobject is to provide a detachable cross-bar construction in which the crossbars are secured in position solely by the.

usual assembly of the switch per so with the enclosing box and the operating member and in which construction all of the usual screw or rivet means of attaching the crossbars are eliminated.

Another object is to provide a novel form of'double-throw switch blade in which the two branches 'or contact arms are spaced approximately parallel with respect to each other and very much nearer together than has previously been possible thus allowing for a greater operating movement and a greater separation of the contact rupturing parts when the switch is in the off position.

Another object is to provide a switch blade of the preceding description having a novel form of cross-bar connector which also functions to insulate the operating crank from the branches or arms of the blade.

Another object is to provide a practical cross-bar construction which is unusually neat, cheap and sturdy and which construction does not obstruct the full view of the switch parts in any of its positions.

In the drawings, my invention isshown as applied to a quick-make and quick-break switch of the form shown in my co-pending application Ser: #293,675 but, features of my invention may be applied to a manually operated switch which has a rigid connection between the switch blades and the operating member.

In the preferred form the switch blade members are forked and two insulating bars connecting the members are arranged between the two branches of each blade. The switch operating member is ivotally supported in the box independbntly of the other switch members and its crank portion is located between the two insulating bars.

Fig. 1 is a perspective view of a switch of one form embodying my invention, the I cover ofthe box being open and partially broken away.

Fig. 2 is a perspective view of the forked blades and the insulating bar connection between the crank and blades.

Fig. 3 is a sectional view and sideelevation of the switch parts. The box 5 and cover 6 may be of any suitable construction. v Figs. 4 and 5 illustrate the difference between my novel doublethrow blade and the old well-known type which it is intended to displace.-

The conducting parts of-the switch are mounted on insulating base 7 which is suit ably secured in the box. The switch may be constructed to take care of any number of poles of a circuit. The form shown is intended for controlling an ordinary two wire or double pole circuit. Each unit has a central post 8 to which is pivoted a movable switch member 9 having two blades or arms 10 and 11 spaced apart from each other and adapted to engage the upper and lower jaws 12 and 13 respectively.

An operating member 14: is pivotall sup ported within the box and has a cran portion located between the insulating cross bars 15 and 16. These insulating bars are held in position between the respective switch members bymeans of projections 17 and recesses 18. These insulating bars serve to insulate the blades from the operatin crank and to connect the adjacent switch blades and are themselves held in lace by the presence of the crank portion of the operating member.

The operating handle 20 on the outside of the box may be of any suitable construction and connected to the crank 14 on the inside in any suitable manner.

Preferably, however, I employ suitable quick-make and quick-break mechanism including the oscillating member 21 and the throwing springs 22 and 23 so as to open and close the circuit with a snap action. This construction is of the double throw type so that one circuit is closed when the switch member 9 is in contact with the jaws 12 and similarly another circuit is closed through the jaws 13 when the switch member 9 is in the opposite position to that shown in Fig. 1.

When the switch is of the quick-make variety I prefer to provide anabutment 24: between the switch units adapted to function as a stop and to receive the impact of the insulating bars 15 and 16,-respectively, when the circuit is closed.

The insulating bars 15 and 16 and the abutment 24 are preferably. of fibre or the like so that they have insulating characteristics and also are somewhat resilient and thus capable of cushionin and distributin the powerful impact wlthout danger o chipping or cracking the base. There is considerable resiliency in the crank itself gr and as the abutment 24 is midway between the opposite ends of the crank, a considerable resilience is provided by the crank itself. 7

Although the axis of the crank is supposed to coincide with the axis of the ivoted switch members, it will be seen that a solute centering is not essential because of the nature of the connection between the crank and the switch members. The cross bar of the crank 14 and the insulating bars 15 and 16 may slide with respect to each other so there is no tendency of the arts to bind when in action, even when t e crank and switch members are not coaxial.

By referring to Fig. 3,.it will be noted that the arm 10 of the blade 9 is in full contact with the stationary contact jaw 12 and is parallel with the surface of the switch base and that the arm 11 of the blade is also in a relatively parallel position.

When the switch is thrown to its other customary to make blades the blades must move contact making position, the relative positions of the blade arms is, of course, reversed;

When the switch is in the intermediate or off position, the blade arms 10 and 11 project at right angles to the base.

Because of the foregoing arrangement, it is necessary that the connecting end of the blade arms be pivoted at a point midway between the arms therefore either a comparatively high hinge post must be provided or, if a regular hinge post be used, it must be supported on a corresponding high plane.

I have provided an operating crank having its bearings in line with the hinge post centers so that the crank does not creep or change its relative position with respect to the cross-bar members during its operating movement.

Among the advantages of this novel blade are that it provides for a maximum contact breaking movement and that it allows for ample pick-up movement of the quickbreak means before the switch operates.

WVith this construction it is possible to remove the screws which secure the switch base to the box and slide the switch down so as to disengage the connecting bars 15 and 16 from the crank 1 1 without dismounting the crank.v Obviously the switch may be inserted in the box and connected with the crank in a reverse order. It will be seen that the insulating cross bars are positively secured in operative position without requiring any screws, rivets or assembling operations.

A comparison between Figs. 4: and 5 illus trates one of the advantages of my novel design of double-throw switch blade overthe old and well known form. It has been of this type substantially as shown in Fi 5 with one blade 10 extending at approximately ninety deees to the other blade 11 and it will readily be seen that, when the switch is moved to off or neutral position, the blades will have moved only forty-five degrees.

In Fig. 4, the blades are shown in the off or neutral position and it will be seen that I full ninety degrees from either of the on positions to the off position.

' This comparatively great operating movement ismade ossible by my substantially parallel type 0 blade. It results in a much greater separation of the contact parts in the switch opening movement and it allows for the application of a substantial quick-make and quick-break mechanism which it is diflicult to obtain in the construction shown in It should be understood that various may made without departing from the spirit or scope of my invention.

- together and an operating member having a crank portion mounted between said insulating bars.

3. In a switch, a number of pairs of stationary contacts, a hinged switch blade mounted between each respective pair of contacts, an operating crank, insulating bars interposed between said crank and portions of the respective switch blades and an insulating abutment adapted to receive the operating impact of said insulating bars.

4. In a double throw switch a pair of pivoted forked switch members each havin two spaced apart and substantially paralldl blades, stationary contacts adapted to receive said blades, an operating crank and insulating bars on opposite sides of said crank between said blades and laterally connecting said blades.

5. A switch including a number of hinged switch blades, a pair of insulating bars securing said blades together in spaced relation and an operating crank having a detachable connection with said insulating bars for securing said bars in position.

6..A switch including a'base, a number of pairs of stationary contacts on said base,

a hinged switch member mounted on said base between each respective pair of contacts, an operating crank, insulating bars connecting said switch member with said crank, and an insulating abutment supported on said base and adapted to receiverthe operating impact of said insulating bars.

7. In a safety switch, a box, an insulating base detachably mounted in said box, a double throw switch blade mounted on said base and having two spaced contact arms, an operating crank pivoted in said box, and insulating cross bars interposed between said crank and the arms of said switc blade.

8. A switch including a number of hinged forked switch blades, two spaced insulating bars connecting the res ective switch blades together and an operating member having a crank portion operably secured between said insulating bars.

9. A switch including a number of pairs of stationary contacts, a forked switch blade pivotally mounted between each respective pair of said contacts, an operating crank two insulating bars on opposite sides of said crank and interposed between said crank and an edge portion of said switch blade and laterally connecting said switch blades, and an insulating abutment adapted to receive the impact of said insulating bars.

10. In a quick-make double throw switch -a pair of pivoted switch members each having two spaced apart and substantially arallel blades, stationary contacts adapte to receive said blades, an operatin crank, insulating bars on opposite sides 0 said crank and laterally connecting said blades, and a resilient abutment for said bars.

11. A double throw switch including, a base, two stationary contact members supported thereby, a hinge member supported on said base between said contact members and projecting beyond the plane of the outer ends of said contact members, a forked switch member pivoted to said hinge member and having two blades adapted to coact respectively with the contact members, an operating crank connected to said switch member between said blades, an operating handle, quick break mechanism having lost motion connecting means between said handle and said crank, said connecting means having an oscillatin member having a throwing movement 0 approximately ninety degrees.

, HERMAN J. HAMMERLY.

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